Cytokine gene signatures in neural tissue of horses with equine protozoal myeloencephalitis or equine herpes type 1 myeloencephalopathy.
Authors: Pusterla N, Wilson W D, Conrad P A, Barr B C, Ferraro G L, Daft B M, Leutenegger C M
Journal: The Veterinary record
Summary
# Editorial Summary Researchers used real-time PCR to quantify pathogen-specific and immune gene expression in post-mortem neural tissue from horses with equine protozoal myeloencephalitis (EPM; *n*=12), equine herpesvirus type 1 myeloencephalopathy (EHV-1; *n*=11), and healthy controls (*n*=12), examining transcription of *Sarcocystis neurona*, *Neospora hughesi*, EHV-1, and eight cytokine markers. *S. neurona* was detected in all EPM cases (mean relative transcription 123-fold baseline; range 1–461-fold), with two horses also harbouring *N. hughesi* cDNA, whilst all EHV-1 cases showed positive viral signals (mean 275-fold; range 1–1618-fold), and no pathogens were detected in controls. The cytokine signatures differed meaningfully between diseases: EPM cases exhibited a predominantly pro-inflammatory Th1 response with consistent IL-8, TNF-α and IFN-γ expression but absent or minimal Th2 markers (IL-4, IL-6, IL-10), whereas EHV-1 cases showed IL-8 upregulation without reciprocal IFN-γ or IL-10 expression and minimal TNF-α. These distinct immune profiles suggest fundamentally different pathogenic mechanisms and may eventually help clinicians differentiate between these clinically similar myeloencephalopathies; the pro-inflammatory bias in EPM particularly warrants investigation of whether targeted anti-inflammatory strategies could mitigate neurological damage alongside conventional antimicrobial therapy.
Read the full abstract on PubMed
Practical Takeaways
- •The distinct cytokine gene expression patterns between EPM and EHV-1 myeloencephalopathy offer potential molecular diagnostic markers to differentiate these neurological diseases in field cases
- •Pro-inflammatory Th1 dominance in EPM suggests targeted immune modulation strategies may warrant investigation as adjunctive therapeutic approaches
- •Real-time PCR analysis of neural tissue cytokine profiles could improve diagnostic accuracy when clinical presentation is ambiguous between these two conditions
Key Findings
- •Sarcocystis neurona cDNA detected in neural tissue of all 12 EPM-affected horses with transcription levels ranging 1-461 times baseline (mean 123)
- •All 11 EHV-1 myeloencephalopathy horses showed positive viral signals with transcription levels 1-1618 times baseline (mean 275)
- •EPM cases showed Th1 pro-inflammatory cytokine profile (IL-8, TNF-alpha, IFN-gamma commonly expressed) with absent or rare Th2 anti-inflammatory response
- •EHV-1 cases displayed IL-8 expression with absent IFN-gamma and rare TNF-alpha, differing from EPM cytokine signature